The present invention relates to internal combustion engines and, more particularly, to devices for supplying oil of different temperatures to such engines.
It is known that the process of supplying an internal combustion engine with lubricating oil suffers from the problem that during normal automotive operation, particularly during the hot summer season, cooling of the lubricating oil is necessary, while during the starting of the engine and when it is operating in the partial load range, particularly during the cold winter season, the oil temperature is not at an optimal value. Therefore, various measures have become known which aim at optimizing the oil temperature. Apart from immersion heater-like heating devices for the oil, which heaters strain the battery in an undesirable manner, devices for automatic control of oil cooling have become known from German Pat. No. 683,901. These devices contain a thermostatically controlled valve which at higher oil temperatures causes oil circulation over an additional oil cooler, but short circuits the oil cooler at lower oil temperatures. A shortcoming of devices of this kind may be seen in the need for an oil cooler which must be connected by way of lines with the oil pan and the valve arranged therein.
German patent application No. M 10 525, discloses an internal combustion engine with an oil pan divided into two sections so that two oil quantities of different temperatures are available. The two chambers communicate with each other and are equipped with suction lines. The bottom of one of the chambers is located at a distance above the bottom of the oil pan. From the two chambers in the oil pan, oil having different temperatures is sucked up by means of separate pumps through separate coolers arranged outside the oil pan. The oil is used partly for piston cooling and partly to supply points in the internal combustion engine with lubrication. In this case, the aim is to obtain, during all operating phases of the internal combustion engine, and thus independent of the prevailing oil temperature resulting from the temperature of the internal combustion engine, two oil circulations with different oil temperatures, i.e., partly for cooling and partly for lubricating.
German Letters of Disclosure No. 2 057 625 also show a reciprocating piston engine with a divided oil pan. However, this construction is suitable only for a stationary machine in that in this specific case, an especially large lubricating oil storage tank is assumed, which tank extends below the internal combustion engine and a current generator driven by the engine. The oil pan is divided into two quite differently sized chambers by means of a perpendicular wall. The extraction of the oil from the pan is obtained through suction lines which in each case are associated with one of the chambers and which, by way of a thermostat valve, pass into a common delivery line. The principle of this known stationary internal combustion engine with regard to an upward limitation of the oil temperature, thus consists in providing a sufficiently large oil volume, and not in creating a device in the manner of an oil cooler. This limitation on the oil temperature also does not involve rendering the design of the internal combustion engine within the limits of the oil pan in such a manner that the necessary cooling is ensured without an investment in an additional oil cooler.
Ribbing of the bottom of an oil pan to cool the oil is known from U.S. Pat. No. 3,521,613. In addition, a mechanical vibration-insulating mounting of an oil pan is described in U.S. Pat. No. 3,695,386.